Break config_default into master_site_configs.

masters/master.client.libyuv/master.cfg

 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # These modules come from scripts/master, which must be in the PYTHONPATH.
 from master import master_utils
 from master import slaves_list
 
 import config
-ActiveMaster = config.Master.Libyuv
+import master_site_config
+ActiveMaster = master_site_config.Libyuv
 
 c = BuildmasterConfig = {}
 c['change_source'] = []
 c['schedulers'] = []
 c['builders'] = []
 c['status'] = []
 
 config.DatabaseSetup(c, require_dbconfig=ActiveMaster.is_production_host)
 
 import master_source_cfg
@@ skipping 19 matching lines @@
     config.Master.GetBotPassword(),
     missing_recipients=['buildbot@chromium-build-health.appspotmail.com'])
 master_utils.VerifySetup(c, slaves)
 
 # Adds common status and tools to this master.
 master_utils.AutoSetupMaster(c, ActiveMaster, mail_notifier=True,
     public_html='../master.chromium/public_html',
     templates=['../master.client.webrtc/templates',
                '../master.chromium/templates'],
     enable_http_status_push=ActiveMaster.is_production_host)